The second World War brought about many profound changes in the housing industry which carried over into the post-war era. The exigencies of war resulted in development of both materials and methods for the creation of large volumes of housing which could be constructed quickly, and inexpensively. Under such circumstances, interior walls of such structures, could not, as a practical matter, abide the luxury of the more time honored, and in the early forties, the more dominant form of interior wall, i.e., lath and plaster. While its durability and effectiveness as a insulator was unquestioned, the time and cost of construction, not to mention scarcity of wire, was unacceptable, and militated against its use.
Thus, the development of dry-wall, a sheet of compressed gypsum-like material sandwiched between two sheets of heavy paper. The product, which typically sold in four foot by eight foot sheets, could be literally thrown up to create an acceptable interior wall quickly and inexpensively. Whatever it may have lacked in aesthetics, in its early usage, was excused by virtue of its expediency.
In the post-war era, and beginning in the early fifties, dry-wall applications in residential housing began to proliferate, notwithstanding the resistance from craftsman who had applied lath and plaster for many years. However, to be acceptable in residential housing, it became necessary to be able to finish the interior wall surface in such a manner that, at least the casual observer would not be able to observe the difference between a dry-wall surface and that of lath and plaster without close examination.
The single most difficult aspect of disguising a dry-wall installation is being able to cover up rough seams between contiguous sheets and to be able to finish off corners so that they have the appearance and smoothness of plaster. While it would be nice to find uniformity in the dry-wall industry, the realities are that every piece is not a perfect four by eight rectangle, nor is every corner square, and when a piece needs to be saw cut to fit a particular space, the likelihood of that piece being "square" is even more remote. Dry-wall seams are typically "taped", and a taping or finishing compound is then smoothed over the taped area in order to visually bring the seams together into a "oneness", which makes the seam appear to disappear. When the seam is in a corner, and particularly a corner in which the contiguous surfaces of the sheets form an obtuse angle, application of the finishing compound becomes even more difficult, while at the same time being more acute in terms of providing the visual appearance of "oneness".